This proposal seeks funding for a national course for renal fellows entitled, "Origins of Renal Physiology," to be held at the Mount Desert Island Biological Laboratory (MDIBL) the week of September 5 - 12, 2009. This is the second offering of this course;the first "Origins" course was held in September 2008, also at the MDIBL. The course consists of six modules, including glomerular filtration, proximal tubule function, thick ascending limb cotransporters, secretion and salt balance, collecting duct ENAC sodium channel function, and osmotic homeostasis. The modules feature classic models of renal physiology such as toad bladders, shark rectal glands, and cultured cell lines combined with modern imaging, molecular biology, developmental biology, and transporter expression techniques. The goals are to reconnect renal fellows with the origins of renal physiology and to broaden their understanding from the (usually) narrow focus of their own research to renal physiology as a whole. Each of the six modules runs in three consecutive 1.5-day rotations (Sunday-Monday, Tuesday-Wednesday, and Thursday-Friday), with the first day of each rotation involving intensive experimental work, and the second day involving analysis and presentation of the work to the entire conference group. Each trainee will complete three of the six planned modules during the three rotations. The modules will not be repetitions - instead the second rotation will conduct experiments that extend or build upon those experiments conducted by the first rotation. The course is described on the MDIBL website: http://www.mdibl.org/courses, and in an editorial published in JASN last April (Zeidel et al., JASN 19: 649-50, 2008). Requested funds will cover a portion of the course tuition charged to all trainees;therefore, tuition costs carried by the trainee will be reduced and increased participation is expected. Relevance: The course "Origins of Renal Physiology" is highly relevant to biomedical research and the advancement of human health. Course participants are 30 renal fellows in their second year of a three-year fellowship. This number represents about 10% of the annual "class" of second year renal fellows in the United States, permitting the course to have a significant impact on the training of fellows nationally. Course faculty includes clinical nephrologists and investigators. The trainees perform experiments to elucidate kidney function including glomerular filtration, proximal tubule, thick ascending limb, and collecting duct transport, water homeostasis, cellular trafficking of transporter proteins, and the structure-function of transporter proteins such as aquaporins, urea carriers, ENaC and the Na/K/2Cl cotransporter.